如何在c++中克服无穷费波纳契级数的负整数输出？

#include <iostream>
#include <boost/multiprecision/cpp_int.hpp>

using namespace boost::multiprecision;
using namespace std;

cpp_int fibonacci(int n) {
    cpp_int a = 0, b = 1, c;
    if (n == 0)
        return a;
    for (int i = 2; i <= n; i++) {
        c = a + b;
        a = b;
        b = c;
    }
    return b;
}

cpp_int fibonacciNegative(int n) {
    if (n % 2 == 0)
        return -fibonacci(abs(n));
    else
        return fibonacci(abs(n));
}

int main() {
    int n = -10;
    cpp_int result = fibonacciNegative(n);
    cout << "Fibonacci number at position " << n << ": " << result << endl;
    return 0;
}